[petsc-users] Solve for all repeated eigenvalues

[Greg Meyer]

(by the way this is a standard Hermitian eigenvalue problem)

On Thu, Jun 28, 2018 at 1:53 PM, Greg Meyer <gregory.meyer at gmail.com> wrote:

> Hi all,
>
> I'm using SLEPc to solve for some eigenvalues. If I ask for the
> eigenvalues with the leftmost real part (using SMALLEST_REAL), and there
> are repeated eigenvalues, it appears that the solver does not always find
> all of the repeated values before jumping up to the next unique eigenvalue.
> For example if the lowest eigenvalues of my matrix are [-12, -10, -10, -10,
> -8], and I request 4 eigenvalues, I may get [-12, -10, -10, -8]. I'm using
> the default solver. Is there any way, or any solver, that ensures that no
> eigenvalues are skipped?
>
> Thanks in advance,
> Greg
>
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